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3    * contributor license agreements.  See the NOTICE file distributed with
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5    * CS licenses this file to You under the Apache License, Version 2.0
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9    *   http://www.apache.org/licenses/LICENSE-2.0
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11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
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17  package org.orekit.models.earth.ionosphere;
18  
19  import org.hipparchus.CalculusFieldElement;
20  import org.orekit.frames.TopocentricFrame;
21  import org.orekit.propagation.FieldSpacecraftState;
22  import org.orekit.propagation.SpacecraftState;
23  import org.orekit.utils.ParameterDriversProvider;
24  
25  /** Defines a ionospheric model, used to calculate the path delay imposed to
26   * electro-magnetic signals between an orbital satellite and a ground station.
27   * <p>
28   * Since 10.0, this interface can be used for models that aspire to estimate
29   * ionospheric parameters.
30   * </p>
31   *
32   * @author Joris Olympio
33   * @author Bryan Cazabonne
34   * @since 7.1
35   */
36  public interface IonosphericModel extends ParameterDriversProvider {
37  
38      /**
39       * Calculates the ionospheric path delay for the signal path from a ground
40       * station to a satellite.
41       * <p>
42       * This method is intended to be used for orbit determination issues.
43       * In that respect, if the elevation is below 0° the path delay will be equal to zero.
44       * </p><p>
45       * For individual use of the ionospheric model (i.e. not for orbit determination), another
46       * method signature can be implemented to compute the path delay for any elevation angle.
47       * </p>
48       * @param state       spacecraft state
49       * @param baseFrame   base frame associated with the station
50       * @param frequency   frequency of the signal in Hz
51       * @param parameters  ionospheric model parameters at state date
52       * @return the path delay due to the ionosphere in m
53       */
54      double pathDelay(SpacecraftState state, TopocentricFrame baseFrame, double frequency, double[] parameters);
55  
56      /**
57       * Calculates the ionospheric path delay for the signal path from a ground
58       * station to a satellite.
59       * <p>
60       * This method is intended to be used for orbit determination issues.
61       * In that respect, if the elevation is below 0° the path delay will be equal to zero.
62       * </p><p>
63       * For individual use of the ionospheric model (i.e. not for orbit determination), another
64       * method signature can be implemented to compute the path delay for any elevation angle.
65       * </p>
66       * @param <T>         type of the elements
67       * @param state       spacecraft state
68       * @param baseFrame   base frame associated with the station
69       * @param frequency   frequency of the signal in Hz
70       * @param parameters  ionospheric model parameters at state date
71       * @return the path delay due to the ionosphere in m
72       */
73      <T extends CalculusFieldElement<T>> T pathDelay(FieldSpacecraftState<T> state, TopocentricFrame baseFrame,
74                                                      double frequency, T[] parameters);
75  }